1. Field of the Invention
The present invention relates in general to electromagnetic signal apparatus and pertains, more particularly, to such an apparatus in which components thereof are relatively slideable. An example of such apparatus is a phase-shifter. Even more particularly, the invention relates to the foregoing apparatus in which means are provided for preventing jamming of and damage to the components during use and adjustment thereof.
2. Background Discussion
In microwave devices, particularly those requiring adjustment of components of the device, such as in a phase-shifter, many times jamming and damage to the device occurs when the user over-adjusts in one direction or the other. Such damage to phase-shifters has become a recurring problem. The damage to the phase-shifter has occurred primarily because the user applies excess torque to the lead screw at either end of the adjustment position. Even with caution being given to users to avoid over-torquing, damage to the phase-shifter is still quite common.
With regard to the aforementioned problem, reference is now made to FIG. 1 which is a prior art cross-sectional view illustrating a simplified version of a phase-shifter that includes a housing 10 having one end wall 11 and a wall 15 for supporting the lead screw 16. The housing 10 also is illustrated in FIG. 1 as supporting input signal connector 12 and output signal connector 14. These connectors couple to stationary conductors 12A and 14A, respectively. Associated with the stationary or fixed conductors is a moveable conductor 18 that is supported by the slider 20. The slider supports a nut 22 that is adapted to engage with the lead screw 16. Rotation of the lead screw 16 at the shaft 24 causes the slider 20 to move toward and away from the end wall 11.
FIG. 1 illustrates the phase-shifter in its maximum phase setting with the slider 20 fully to its left position. This position illustrates the aforementioned problem in that the slider 20 bottoms out at 25 against the end wall 11. The threads of the lead screw 16 can thus easily become stripped if too much torque is applied at the shaft 24. The same type of operation can also occur when the lead screw is rotated in the opposite direction by the shaft 24. In that instance the right most end of the slider 20 can bottom out against the wall 15 and also cause jamming, stripping of threads and damage to the phase-shifter.